perf: Optimize pos_to_line_col() calculation for big input data

[xor2003]

Code review checklist

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR)
• Title summarizes what is changing
• Commit messages are meaningful (see this for details)
• Tests have been included and/or updated
• Docstrings have been included and/or updated, as appropriate
• Standalone docs have been updated accordingly
• Changelog(s) has/have been updated, as needed (see CHANGELOG.md, no need
  to update for typo fixes and such).

[coveralls]

Coverage increased (+0.1%) to 91.172% when pulling 9dc3f72 on xor2003:master into 04bb549 on igordejanovic:master.

[igordejanovic]

@xor2003 Looks good. Thanks!